Process for crimping uncrosslinked fibers



Nov. 20, 1951 L. w. RAINARD 2,575,339

PROCESS FOR CRIMPING UNCROSSLINKED FIBERS ed 5, 194a INVENTOR.

L50 W. Emu/e20 ATTOENE Y Patented Nov. 20, 1951 PROCESS FOR CRIMPING UNCROSS- LINKED FIBERS Leo W. Rainard, Nyack, N. Y., assignor to Alexander Smith, Incorporated, a corporation of New York Application December 15, 1948, Serial No. 65,440

5 Claims.

This invention relates to the treatment of uncross-linked fibers, and more particularly to a process for imparting an artificial crimp to vegetable fibers and uncross-linked synthetic thermoplastic fibers, and has for an object to provide a fiber of the above type having novel and improved characteristics.

Another object is to produce a fiber of the above type characterized by a predominance of sharp, angular bends or crimps with the portions between bends substantially straight.

v Another; object is to provide an artificially crimped fiber of the above type having improved carding and spinning characteristics.

Other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

In accordance with one embodiment of this invention, the crimp is produced mechanically by feeding the fibers in the form of a roving or slubbing between feed rolls into a crimping chamber which is maintained full of fibers under a predetermined temperature and back pressure. As the fibers are forced into the crimping chamber, they are laid in a zig-zag form and are pressed to form angular bends or crimps with intervening straight portions, the length of which depends upon several factors, such as the nature of the fibers and the temperature and pressure to which the fibers are subjected in the crimping chamber. The temperature in the crimping chamber should be in the range below which the natural resilience of the fibers resists deformation and above which degradation occurs, the relationship being such that the fibers are brought to the plastic condition necessary for the formation of a permanent crimp. The crimp is set by rapid cooling in a cooling chamber.

The novel features which are characteristic of this invention will be better understood by referring to the following description, taken in con-' nection-with the accompanying drawings in which a specific form of crimping apparatus has been set forth for purposes of illustration.

In the drawings:

Fig. l is a side elevation of an apparatus embodying the present invention;

Fig. 2 is a top plan view thereof on a larger scale; and

Fig. 3 is a vertical section taken along the line 3-3 of Fig. 2.

Referring to the drawings more in detail, the crimper is shown as comprising a frame l carrying a pair of feed rolls H and I2 and drive shaft l3. The shaft I3 is journalled in the frame I I] and carries a pinion l5 and a sprocket 14 which is driven by suitable means, not shown. The feed roll II is keyed to a shaft I6 journ'alled in bearing blocks I! fixed to the frame [0 and carrying a gear l8 meshing with the pinion l5.

. 2 The feed roll I2 is keyed to a shaft 20 journalled in bearing blocks 2| which are slidable in the frame I. The roll I2 is held in pressure engagement with the material fed between the rolls by springs 22 seated around threaded rods 23 which bear against the bearing blocks 2|. The rods 23 extend through'a bracket 24 attached to the frame I0 and carry nuts 25 and adjusting knobs 26. The nuts 25 are held against rotation by the frame Ill. The springs 22 are seated between the nuts 25 and the bracket 24 and their tension may be adjusted by means of the knobs 26.

The shaft 20 carries a gear meshing with the gear I8. The gears l8 and 30 have teeth of sufficient depth to remain in mesh th.roughout. the normal range of sliding movement of the shaft 20 during the operation of the crimper.

Positioned below the rolls l I and I2 is a vertical tube 33 having a conical bore 34, forming a cooling chamber. The tube 33 is attached to a saddle 35 having a tapered central bore 36 forming a crimping chamber and having a curved upper surface 31 conforming to the bight of the rolls I l and I2 and machined to have a slight running clearance from the surface of the rolls. The saddle 35 is attached to the frame ID by suitable means and is formed with a plurality of radial passages 42 for the injection of a heating agent such as hot air into the crimping chamber. The

radial passages 42 communicate with an annular passage 43 in the saddle 35 which is closed by a collar 44 to form an inlet manifold. The fluid is supplied to the annular passage 43 by a pipe 45 registering with a port 46 in said collar.

A cooling agent, such as cold air, is introduced into the cooling chamber through radial passages 41 communicating with an annular passage 48 in the tube 33 which is closed by a collar 49.

A cold air supply duct 51 communicates through the collar 49 with the annular passage 48. The

passages 41 are preferably located about midway of the length of the cooling chamber so that the entire mass of fibers therein will be subjected to the cooling air.

At its lower end the tube 33 carries a flanged extension 50 to which a pair of doors 52 are hinged by hinges 53 and are held closed against the tapered end 54 of the extension 50 by weights '55 attached to arms 56 secured to the doors.

In the operation of the crimper, the rolls ll and 12 are driven by any suitable source of power and the fibers to be crimped are fed thereto over a guide roll 58, preferably in the form of a rope or a web 59. The fibers are held in the crimping and cooling chambers by the doors 52 until they have been packed sufliciently to force the doors slightly open againstthe force of the weights 55. The back pressure of the packed fibers causes the fibers which are being forced against the packed fibers by the feed rolls to be folded over in zig-zag crimp the spacing of which depends upon the nature of the fibers, the temperature, and the back pressure.

The heating agent, such as hot air, is intro duced through the pipe and passages 42 into the mass of packed fibers and is controlled so as to raise the fibers in the crimping chamber to the desired temperature for crimping.

The raw fibers may be treated in the usual manner to form stock. This pretreated stock is fed directly at a uniform rate to the feed rolls I I and 12 of the crimper or may be fed to a webforming device, such as a card, and fed as a web or condensed into a rope which is fed to the feed rolls Ii and I2 as a sliver or slubbing 59. If a more uniform feed is required, the stock may be picked and carded and condensed to a rope for the above purpose after one or more stages of carding. A uniformity in density of feed stock is preferred to prevent jamming or slipping at the feed rolls or undue lateral movement of the feed rolls.

' In either case, the fibers are stufled by the feed rolls H and i2 into the crimping chamber and through the cooling chamber and are forced out of the bottom of the cooling chamber against the pressure exerted by the discharge doors 52.

The back pressure at the entrance of the crimping chamber controls the size of the crimp, a higher pressure causing a finer crimp (more crimps per inch) and vice versa.

For higher temperatures, steam under pressure may be used. The quality of steam should be selected to cause the fibers to reach the desired temperature and moisture content. Due to the packing of the mass of fibers, they are relatively impermeable to steam and steam pressures suited to produce the desired high temperatures may be used.

The hot fluid may be injected under conditions to raise the temperature of the fibers to a point to bring the fibers to a plastic condition to permit the crimps to form therein, for example, to a temperature of 212 F. to 300 F. and the cooling in the cooling zone may be controlled to cool the fibers to a temperature below that at which they are in a plastic condition so as to set the crimps while the fibers are still held under pressure and before discharge thereof from the cooling zone. The time should be sufiicient to permit all of the fibers to reach the necessary temperatures in the crimping and cooling zone, one or two minutes usually being suificient.

The crimpedfibers emerge from the crimper in the form of a very condensed tow or rope, which is easily opened and separated.

The fibers may be carded, formed into a roving and spun in the usual manner and skein dyed if desired, or they may be picked to open the fibers and stock dyed after which they may be carded and spun into yarn. The entanglement of the fibers due to the predominance of angular bends causes the fibers to interact more strongly and in carding the uniform distribution of the fibers over the card cylinder is greatly facilitated. The sliver from the card cylinder is more readily condensed into a uniform round and full roving which can be drawn out to produce a substantial reduction in diameter and spun without breaking. The yarn made from such artificially crimped fibers is characterized by more resilience and fullness than similarly prepared yarn made from fibers which have not been subjected to this process of crimping. The artificially crimped assessefibers may also be blended with other fibers and formed into yarn if desired.

This process is particularly applicable to vegetable fibers, such as cotton, hemp, jute, ramie and fiax, and to uncrosslinked thermoplastic synthetic fibers, such as viscose rayon, acetate rayon, nylon, condensation products of terephthalic acid and glycol (teryiene) and polyvinylidine chloride products, either in staple or filament form. These fibers have the characteristic of being thermoplastic to an extent such that they may be softened by heat to permit mechanical crimping and set immediately on cooling.

The process and apparatus may be varied as will be apparent to a person skilled in the art.

What is claimed is:

1. The method of imparting a permanent artificial crimp to vegetable fibers and uncrosslinked thermoplastic synthetic fibers, which comprises gripping said fibers between closely spaced conveyor surfaces discharging into a substantially closed crimping zone, and forcing the gripped fibers into said zone against the pressure of a mass of fibers held compacted under pressure in said zone, said pressure being adapted to cause the fibers to be progressively folded over and crimped as they are delivered from said conveyor surfaces, holding the mass of crimped fibers compacted under a substantially constant pres- 'sure to retain the crimp therein, injecting a hot fluid into the mass of fibers in said zone to heat the fibers to a temperature to bring the fibers to a plastic condition in which permanent angular bends are formed at the folds therein, advancing said fibers while held under said pressure through a cooling zone, cooling the fibers in said cooling zone to a temperature below that at which they are in a plastic condition to set said crimps and discharging the crimped fibers from said cooling zone.

2. The method set forth in claim 1 in which a cooling fluid is introduced into the mass of fibers in said cooling zone.

3. The method set forth in claim 1 in which hot air is introduced into the mass of fibers in said crimping zone for heating the same.

4. The method set forth in claim 1 in which hot air is introduced into the mass of fibers in said crimping zone for heating the same, and cold air is introduced into the mass of fibers in said cooling zone.

5. The method set forth in claim 1 in which the fibers are heated to from 212 F. to 300 F. in the crimping zone and are cooled below 180 F. in the cooling zone.

LEO W. RAINARD.

'nEEERENcEs CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,139,543 Finlayson et al. Dec. 6, 1938 2,204,341 Cobb June 11, 1940 2,208,632 Dreyfus July 23, 1940 2,300,791 Lodge Nov. 3, 1942 2,311,174 Hitt Feb. 16, 1943 2,321,757 Lodge June 15, 1943 2,394,165 Getaz Feb. 5, 1946 2,428,046 Sisson et al. Sept. 30, 1947 2,434,533, Wurzburger Jan. 13, 1948 2,504,183 Croft Apr. 18, 1950 2,505,618 Hammerle Apr. 25, 1950 2,514,557 Pfau June 11, 1950 

1. THE METHOD OF IMPARTING A PERMANENT ARTIFICIAL CRIMP TO VEGETABLE FIBERS AND UNCROSSLINKED THERMOPLASTIC SYNTHETIC FIBERS, WHICH COMPRISES GRIPPING SAID FIBERS BETWEEN CLOSELY SPACED CONVEYOR SURFACES DISCHARGING INTO A SUBSTANTIALLY CLOSED CRIMPING ZONE, AND FORCING THE GRIPPED FIBERS INTO SAID ZONE AGAINST THE PRESSURE OF A MASS OF FIBERS HELD COMPACED UNDER PRESSURE IN SAIDA ZONE, SAID PRESSURE BEING ADAPTED TO CAUSE THE FIBERS TO BE PROGRESSIVELY FOLDED OVER AND CRIMPED AS THEY ARE DELIVERED FROM SAID CONVEYOR SURFACES, HOLDING THE MASS OF CRIMPED FIBERS COMPACTED UNDER A SUBSTANTIALLY CONSTANT PRES- 